Using the average rate of change, the rate of speed over the interval [9, 11] is of 2.5 miles per hour.
The average rate of change of a function is given by the change in the output divided by the change in the input. Hence, over an interval [a,b], the rate is given as follows:
[tex]r = \frac{f(b) - f(a)}{b - a}[/tex]
Researching this problem on the internet, we have that:
r = (11 - 6)/(11 - 9) = 2.5.
The rate of speed over the interval [9, 11] is of 2.5 miles per hour.
More can be learned about the average rate of change of a function at https://brainly.com/question/24313700
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